The invention relates to an optical storage apparatus using a removable medium such as magnetooptical cartridge, phase-change type optical disk, DVD-RAM, or the like and, more particularly, to an optical storage apparatus for executing an access of a command while deciding an optimum light emitting power by a test writing on a medium when receiving a host command.
An optical disk has been highlighted as a storage medium serving as a core of multimedia which has rapidly been developed in recent years. For example, in case of an MO cartridge of 3.5 inches, in addition to conventional medium of 128 MB, medium of a high-density recording of 540 MB or 640 MB has also been being presented in recent years. In the MO cartridge which is used in an optical disk drive, a ZCAV recording (zone constant angular velocity recording) in which a medium track is divided into zones and the number of sectors is set to be equal every zone is used. The medium of 128 MB uses the recording method of a pit position modulation (PPM). It is sufficient that the light emitting power changes at three stages of a reading power, an erasing power, and a recording power. On the other hand, the media of 230 MB, 540 MB, and 640 MB use the recording method of a pulse width modulation (PWM) in order to raise a recording density. In the PWM recording, it is necessary to change the light emitting power at four stages of the reading power, the erasing power, a first writing power, and a second writing power. In the PWM recording of a medium of a direct overwrite corresponding type which doesn""t need the erasing operation, it is necessary to change the light emitting power at four stages of the reading power, an assisting power, the first writing power, and the second writing power.
However, in the recording medium of a high density such as 540 MB or 640 MB in which the PWM recording is performed, a margin of an optimum writing power of a laser diode which is used for medium recording is narrow. When a temperature of the medium changes, the optimum writing power changes. The optimum writing power also changes depending on manufacturing conditions of the medium or a difference of writing performance of the optical disk drive. That is, in case of recording by a predetermined writing power which was unconditionally determined at a designing stage, the writing power largely deviates from the actual optimum writing power and a case where the recording operation cannot be executed occurs, so that there is a problem that writing and reading performance deteriorates.
According to the invention, there is provided an optical storage apparatus constructed in a manner such that even when there is a difference of performance of apparatuses or manufacturing conditions of media or when an apparatus temperature changes, an optimum writing power can always be set and, further, even when it takes a long time for a process to set the optimum power, an error due to a time-out doesn""t occur for an upper apparatus.
An optical storage apparatus of the invention comprises: a tight emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a division test writing processing unit for dividing a test writing process to an optimum light emitting power by executing a test writing on the medium into a plurality of processes and for sequentially executing the divided processes each time an upper command is received. By the division test writing process as mentioned above, a series of test writing processes accompanied with the erasing, writing, and reading operations (in the direct overwrite corresponding type medium which doesn""t need the erasing operation, the test writing process for writing and reading) when the upper command is received are divided into a plurality of processing stages and are sequentially executed. Even when the apparatus temperature rapidly changes and the optimum power remarkably deviates from the default power which has initially been set and it takes a long time up to the end of the test writing operation to find the optimum power, since the processes are distributed and executed, a time-out for the upper command doesn""t occur and the recording and reproducing operations can be executed as much as possible even when the power is deviated from the optimum power, so that the apparatus performance is improved.
An optical storage apparatus of the invention comprises: a light emitting power adjusting unit for adjusting a light emitting power of a laser diode which is used for recording and reproduction of a medium; and a division test writing processing unit for dividing a test writing, process to determine an optimum light emitting power by executing a test writing on the medium into a plurality of processes and for sequentially executing the divided processes each time an upper command is received. By the division test writing process as mentioned above, a series of test writing processes accompanied with the erasing, writing, and reading operations (in the direct overwrite corresponding type medium which doesn""t need the erasing operation, the test writing process for writing and reading) when the upper command is received are divided into a plurality of processing stages and are sequentially executed. Even when the apparatus temperature rapidly changes and the optimum power remarkably deviates from the default power which has initially been set and it takes a long time up to the end of the test writing operation to find the optimum power, since the processes are distributed and executed, a time-out for the upper command doesn""t occur and the recording and reproducing operations can be executed as much as possible even when the power is deviated from the optimum power, so that the apparatus performance is improved.
The division test writing processing unit comprises a division executing unit and a division control unit. The division executing unit divides the test writing process into a plurality of processes and executes. When receiving the upper command, the division control unit discriminates about the necessity of the test writing. When it is determined that the test writing is needed, the division control unit skips to the head of the unexecuted processes in the division executing unit and allows the dividing process of the test writing operation to be executed for a predetermined time. Each time one of the division executing processes is finished, the division control unit preserves the processed number and a processing result. When the elapsed time from the start of the dividing process is shorter than a predetermined time, the processing routine advances to the next dividing process. When a predetermined time elapses, the division control unit interrupts the processes and waits for a next upper command. When the elapsed time from the preceding dividing process by the division executing unit to the present dividing process is longer than a predetermined time, the division control unit cancels the processed numbers and processing results of up to the preceding time and again executes the dividing processes from the beginning. When the interrupting time of the dividing process becomes too long, there is a case where the optimum power fluctuates due to the temperature change or the like during the interrupting time. In this case, a more accurate optimum power is found by again executing the processes from the beginning.
For example, the division executing unit is constructed by:
a first division executing unit for setting a predetermined initial light emitting power (default value) at the first time and for setting a light emitting power obtained by changing the initial light emitting power by every predetermined value at the next and subsequent times;
a second division executing unit for erasing a test area of a medium by the set light emitting power;
a third division executing unit for writing a predetermined test pattern into the erased test area;
a fourth division executing unit for reading out the test pattern written in the test area; and
a fifth division executing unit for deciding the number of times of data dissidence (error rate) by comparing the test pattern with the read-out pattern and for calculating the optimum light emitting power on the basis of the number of times of dissidence obtained by the test writing operations of a plurality of times by the first to fourth division executing units.
In this instance, as for the medium of the direct overwrite corresponding type which doesn""t need the erasing operation, the division executing unit is constructed by:
a first division executing unit for setting a predetermined initial light emitting power (default value) at the first time and for setting a light emitting power obtained by changing the initial light emitting power by every predetermined value at the next and subsequent times;
a third division executing unit for writing a predetermined test pattern into a test area;
a fourth division executing unit for reading out the test pattern written in the test area; and
a fifth division executing unit for determining the number of times of data dissidence (error rate) by comparing the test pattern with the read-out pattern and for calculating an optimum light emitting power on the basis of the number of times of dissidence obtained by the test writing operations of a plurality of times by the first to fourth division executing units.
The division control unit has an-elapsed time control unit for controlling by discriminating whether the division test writing process is performed or not on the basis of the elapsed time from a predetermined start timing of the apparatus. In this instance, as a start timing, in addition to the timing when the medium is loaded into the apparatus, a recovery timing from a sleeping mode in which a servo unit and a spindle motor are stopped, and the like are also included. The elapsed time control unit effectively operates for a period of time until the elapsed time from the start timing such as a loading of the medium or the like reaches a predetermined time, thereby controlling a plurality of division executing units. That is, a temperature in the apparatus rapidly rises and a distribution of the internal temperatures becomes fairly uneven for a period of time until about two to three minutes elapse after the medium was loaded in association with the power-on of the apparatus, so that the apparatus is in a state in which a detection value of the temperature sensor cannot be guaranteed. Therefore, the necessity of the test writing is discriminated on the basis of the elapsed time in a manner such that when the elapsed time from the medium loading is short, the test writing is executed at a high frequency and, when the elapsed time becomes long and the temperature becomes stable, the frequency of the test writing is reduced. That is, the elapsed time control unit decides the optimum light emitting power by executing a plurality of test writing processes in a lump by the first upper command and also sets a valid time Tv when it is unnecessary to adjust the optimum light emitting power on the basis of the elapsed time at that time. After the first time, the elapsed time control unit inhibits a division test writing for the upper command until a predetermined rate time of the valid time Tv elapses, and executes the division test writing in response to the upper command for a period of time until the valid time Tv from the predetermined rate time. The elapsed time control unit sets the valid time Tv so as to be gradually extended in proportion to the elapsed time after the start timing. The elapsed time control unit inhibits the division test writing for a time zone that is shorter than, for example, 90% of the valid time and permits the division test writing for a time zone exceeding 90% of the valid time. When the elapsed time exceeds the valid time Tv during the executing stage of the division test writing, since there is a possibility that the optimum power is remarkably deviated, the elapsed time control unit executes the remaining division test writing in a lump by a next upper command in this case.
On the other hand, the division control unit has a temperature change control unit for controlling by discriminating whether the division test writing process is executed or not on the basis of a change in apparatus temperature. The temperature change control unit operates after that a predetermined time during which the elapsed time control unit operates, for example, 160 seconds elapses from the start timing of the apparatus and the temperature in the apparatus became stable. The temperature change control unit detects the temperature in the apparatus every predetermined time and, when a temperature difference between the preceding detection temperature and the present temperature exceeds a predetermined temperature, for example, 3xc2x0 C., allows the dividing process to be executed. When the temperature difference exceeds an upper limit temperature, for example, 4xc2x0 C. that is higher than a predetermined temperature of 3xc2x0 C., during the interruption of the dividing process, there is a possibility that the optimum power largely changes. Therefore, in this case, the temperature change control unit allows the division executing unit to execute the dividing processes in a lump. When the temperature difference between the preceding and present dividing processes exceeds a predetermined temperature, for example, 2xc2x0 C. during the dividing processes by the division executing unit, there is a possibility that the interrupting time in the dividing state is too long and the optimum power remarkably changes. Therefore, the temperature change control unit cancels the processed numbers and processing results up to the preceding time and again executes the dividing processes from the beginning.
According to the invention, a medium is divided into a plurality of areas in the radial direction, for example, into an inner rim area, an intermediate area, and an outer rim area and the processes by the division test writing processing unit and the division control unit are independently executed every area. This is because the CAV is used for the rotation control of the medium and peripheral speeds in the radial direction of the medium differ, so that laser powers for heating the medium also differ. Therefore, the optimum power of each area is found by dividing the medium into, for example, three areas and independently executing the division writing test every area. Since the medium is divided into a plurality of zones in the radial direction, a plurality of zones are divided into groups every plurality zones in the radial direction, thereby dividing into a plurality of areas. The processes by the division test writing processing unit and the division control unit are independently executed every area.
Further, according to another embodiment of the invention, it is also possible to sequentially execute the division test writing processes by the division test writing processing unit in accordance with a predetermined time schedule of an elapsed time without depending on an upper command. When a temperature change of a predetermined value or more occurs, it is also possible to sequentially execute the division test writing processes by the division test writing processing unit without depending on the upper command.
The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description with reference to the drawings.